Most small businesses overpay tax not because they miss the exotic deductions, but because they never cleanly capture the ordinary ones. A deduction lowers the income you are taxed on, so every legitimate business expense you track is money you keep. The problem is rarely knowing that a deduction exists. It is having books good enough to prove it.
Here are the deductions that matter most for a growing business, the ones people leave on the table, and the bookkeeping habit that decides whether you actually get to claim them.
What counts as a deductible business expense
The IRS standard is short and worth memorizing: an expense is deductible if it is ordinary and necessary for your trade or business. Ordinary means common in your industry. Necessary means helpful and appropriate for the business. Source: IRS Publication 535, Business Expenses.
That covers most of what you already spend to operate. The deductions people miss are usually the ones that blur the personal and business line (home office, vehicle, phone) or the ones that require a decision before year-end (equipment, retirement).
The core deductions most small businesses can claim
These are the workhorses. Each one lowers taxable income directly.
- Payroll and contractor pay: wages, benefits, and payments to 1099 contractors
- Rent and utilities: office, warehouse, or shop space and the services to run it
- Software and subscriptions: the tools your business runs on
- Professional services: accounting, legal, and consulting fees
- Marketing and advertising: ads, design, website, and content
- Insurance: liability, property, and other business coverage
- Business travel and meals: travel in full, and qualifying meals at the current IRS percentage
The deductions owners most often miss
These require a little more discipline, which is exactly why they get skipped.
Home office. If you use part of your home regularly and exclusively for business, you can deduct a portion of your housing costs, either by the simplified square-footage method or actual expenses. Many owners skip it out of an old fear that it triggers audits; used correctly and documented, it is a standard deduction.
Vehicle use. Business mileage is deductible at the IRS standard mileage rate or by actual costs. The rate changes yearly, so confirm the current figure. The requirement that trips people up is a contemporaneous mileage log.
Retirement contributions. A SEP-IRA or Solo 401(k) lets an owner move a large chunk of profit into tax-advantaged retirement savings, often the single biggest lever a profitable owner has. Contribution limits are set annually by the IRS.
Qualified business income (QBI). Most pass-through owners can deduct up to 20% of qualified business income under Section 199A, subject to income thresholds. Source: IRS, Section 199A. It is claimed on your return, but your entity and salary choices affect how much you get.
Equipment: Section 179 and bonus depreciation
When you buy equipment, vehicles, or certain property, you can often deduct the cost faster than the old multi-year depreciation schedule. Section 179 lets you expense qualifying purchases in the year you place them in service, up to an annual limit set by the IRS. Bonus depreciation is a separate accelerator that has been changing under recent tax legislation, so the percentage you can take depends on the current-year rules.
Because both the limits and the bonus percentage move with legislation, this is one area where a year-old article will steer you wrong. Confirm the current-year figures before you time a large purchase, the timing can shift a five-figure deduction between tax years.
Standard deductions at a glance
A quick reference for the categories above and what each requires.
| Deduction | What it covers | What you need to claim it |
|---|---|---|
| Home office | Portion of housing costs | Regular + exclusive business use; square footage |
| Vehicle | Business mileage or actual costs | Contemporaneous mileage log |
| Retirement (SEP / Solo 401k) | Owner retirement savings | Plan set up by the deadline; profit to fund it |
| Section 179 | Equipment and qualifying property | Placed in service in the tax year |
| QBI (Section 199A) | Up to 20% of pass-through income | Eligible income under the thresholds |
| Meals | Qualifying business meals | Receipt, business purpose, who attended |
The deductions only count if your books can back them up. See how Exact keeps your books deduction-ready all year so nothing gets left on the table at filing.
Why do small businesses miss deductions they qualify for?
Small businesses miss deductions mostly because their bookkeeping is incomplete, not because they lack knowledge of the tax code. A deduction you cannot document is a deduction you cannot safely claim.
The pattern we see across client work is consistent:
- Expenses paid from a personal card and never captured
- Mileage and home-office use estimated at year-end instead of logged
- Receipts for meals and travel missing the business purpose
- Equipment purchases timed without regard to Section 179 limits
- Retirement plans set up too late to fund for the year
Clean, current books fix all five. That is the real work behind a lower tax bill, and it is why the cost of good accounting usually pays for itself in deductions captured.
Frequently asked questions
Can I deduct expenses I paid before the business made money?
Yes, within limits. The IRS lets you deduct a capped amount of startup and organizational costs in your first year and amortize the rest. Keep the receipts from before you opened; they are deductible once you are operating.
Are business meals still deductible?
Qualifying business meals are deductible at the percentage the IRS sets for the year (the temporary 100% pandemic-era rule has expired). You need the receipt, the business purpose, and who was there. Entertainment, separately, is generally not deductible.
Does an LLC or S-corp change which deductions I can take?
The ordinary-and-necessary expense deductions are largely the same across structures. Where the entity choice matters is payroll tax and the QBI interaction, which we cover in our guides to S-corp vs LLC taxes and small business tax planning.
Should I keep receipts if my accounting software already tracks expenses?
Yes. Software categorizes the transaction, but for audit support you still need the underlying receipt and, for meals and travel, the business purpose. Digital copies are fine.
Capturing every deduction is a bookkeeping problem before it is a tax problem. Exact keeps your books clean and audit-ready year-round, so at filing time the deductions are already documented. Talk to Exact about your business taxes.
About the author. This article was written by Dan Spada, CPA, at Exact Partners, a national outsourced accounting, fractional CFO, and business tax firm named No. 191 on the 2025 Inc. 5000 list of America’s fastest-growing private companies. Dan and the Exact team help growing businesses keep clean books and capture the deductions they qualify for. Learn more about Dan Spada and the Exact Partners team.
This article is general information, not tax advice for your specific situation. Deduction rules and limits change and vary by situation. Confirm current-year figures with a qualified tax advisor.
